This invention relates to synthetic polymers useful for preparing polymer-immobilized compounds including polymer-supported photosensitizers. The immobilized compounds can be covalently bound to the polymer or bound by electrostatic attraction to cationic groups covalently bound to the polymer backbone. The polymer-immobilized compounds have superior properties when used as photosensitizers. The invention further relates to methods of generating singlet oxygen with the polymer-immobilized photosensitizers for use in synthetic organic chemistry and other applications.
U.S. Pat. No. 4,104,204 discloses polymer-immobilized photosensitizing dyes for producing singlet oxygen. The immobilized dyes are prepared by mixing commercial ion exchange resins with the free ionic dye and filtering off the resulting polymer. Dye is bound through attraction of opposite charges. An anion exchange resin IRA-400(trademark) (Rohm and Haas, Philadelphia) was used to bind the anionic dye Rose Bengal. The resin is a cross-linked polystyrene polymer to which trimethylammonium groups are attached by chloromethylation of the aromatic rings followed by substitution of the chlorine with trimethylamine.
U.S. Pat. No. 4,315,998 discloses covalently linked polymer-immobilized photosensitizing dyes for producing singlet oxygen. The preferred polymer was chloromethylated polystyrene crosslinked with divinylbenzene.
Polymer-immobilized photosensitizers perform optimally when placed in a solvent which causes substantial swelling or physical expansion of the polymer matrix. Prior art polymer-immobilized photosensitizers either do not swell appreciably or swell only in water-immiscible organic solvents. Polymer-immobilized photosensitizers which swell in water or water-miscible organic solvents are needed.
U.S. Pat. No. 3,065,272 discloses vinylbenzylphosphonium ion monomers stated to be useful in the preparation of polymers. Various organic or inorganic anionic counterions are described
U.S. Pat. No. 3,958,995 discloses the preparation of poly(styrene-co-vinylbenzyltributylphosphonium chloride-divinylbenzene). The polymer contained a 49.5/49.5/1.0 ratio of monomer units.
U.S. Pat. No. 4,069,017 discloses a poly(vinylbenzyltrioctylphosphonium chloride) polymer useful in mordant compositions. The polymer is used in an assay for bilirubin.
European Patent Application EP348532A discloses poly(-vinylbenzyltributylphosphonium chloride-co-divinylbenzene). The polymers contain various percentages of divinylbenzene units for crosslinking.
U.S. Pat. No. 5,431,845 discloses water-soluble poly(-vinylbenzyltributylphosphonium chloride) polymers including one in which Rose Bengal is covalently linked. The polymer was prepared by reacting polyvinylbenzyl chloride with a limiting amount of the dye followed by reaction with an excess of tributylphosphine. The polymer thus comprised a non-cross-linked poly(vinylbenzyltributylphosphonium chloride in which a small percentage of the monomer units contained Rose Bengal molecules instead of tributylphosphonium groups.
Polyvinylbenzyldiethylphenylphosphonium salts are disclosed in a patent only as a copolymer with styrene (Jpn. Kokai Tokkyo Koho, JP 63243964 A2 Oct. 11, 1988).
Polyvinylbenzyltriphenylphosphonium salts are well known in the literature, being used as surfactants, phase-transfer catalysts and reagents in organic synthesis. Copolymers of polyvinylbenzyltriphenylphosphonium salts with acrylic acid, butadiene and divinylbenzene are known. None of the foregoing polymers or copolymers have been used as enhancers of chemiluminescence. No reports of covalently attached fluorescers to these polymeric phosphonium salts have been made.
We have developed certain synthetic polymers useful for preparing polymer-immobilized compounds. The polymers have been used to immobilize photosensitizing dyes thereon. The polymers contain a plurality of phosphonium or ammonium cationic groups and are cross-linked to render the polymer insoluble in common solvents. The immobilized compounds are either bound covalently through a linker to the polymer backbone or are bound by electrostatic attraction to cationic ammonium or phosphonium groups covalently bound to the polymer backbone. The polymers and polymer-immobilized compounds have superior properties when compared to known polymer-supports. Polymer-supported photosensitizers of the invention are unexpectedly superior in catalyzing the photosensitized oxidation of compounds containing carbon-carbon double bonds.